Debris Interface Control Device for Wellbore Cleaning Tools

ABSTRACT

A spacing device is located on a lower end of a debris removal tool. Circulation through the tool extends telescoping members to the top of the debris zone against a bias that retracts the members when there is no flow through the tool. The lowest telescoping member has peripheral slots through which the circulation for the tool takes place. The landing of the tool on top of the debris can be detected by the weight indicator at the surface. The device prevents embedding the lower end of the tool into the debris. Instruments can also determine the scope of the telescoping extension and transmit that value to the surface so that the cleanup tool can be continuously spaced from the moving top of the debris pile by maintaining a target distance for extension of the telescoping assembly.

FIELD OF THE INVENTION

The field of the invention is debris cleanup tools for subterranean locations and more particularly to a device attached to the lower end of such tools, regardless of their flow patterns that maintain the tool out of the dense debris as the debris is collected to avoid loss of collection efficiency.

BACKGROUND OF THE INVENTION

Milling operations at subterranean locations involve fluid circulation that is intended to remove cuttings to the surface. Some of these cuttings do not get transported to the surface and settle out on a wellbore support such as a packer or bridge plug that is below. In open hole situations the wellbore can collapse sending debris into the borehole. Over time sand and other debris can settle out on a borehole support and needs to be removed for access to the support or to allow further subterranean operations.

Wellbore cleanup tools have been used to remove such debris. Different styles have developed over time. In a traditional style the motive fluid goes through the center of the tool and out the bottom to fluidize the debris and send the debris laden stream around the outside of the tool where a diverter redirects flow through the tool body. A receptacle collects the debris as the clean fluid passes through a screen and is discharged above the diverter for the trip to the surface.

Another type of tool has a jet stream going downhole outside the tool to drive debris into the lower end of the tool where debris is collected and clean fluid that passes through a screen is returned to the surface outside the tool through ports located near the downhole oriented jet outlets. The jet outlets act as an eductor for pulling in debris laden flow into the lower end of the tool. Some examples of such tools are U.S. Pat. Nos.: 6,176,311; 6,607,031; 7,779,901; 7,610,957; 7,472,745; 6,276,452; 5,123,489.

One operating problem of such tools is that if they are lowered too fast or too much the lower end can penetrate the upper surface of the accumulated debris. When this happens, the efficiency of the debris collection is greatly diminished. Currently the crew at the surface has some idea of the location of the debris and lowers the cleanup tool to the expected debris location. The way that the crew determines when the debris is reached is the weight indicator. When the string finds support the indicated weight is reduced on the surface weight indicator. However, if the surface personnel is not attentive or lowers the debris removal tool too fast they may not be aware that it is embedded in debris and collecting virtually none of it.

Ideally, the debris removal tool should give an indication of its arrival at the top of the debris pile before the collection tool is embedded in the debris zone. The nature of the debris filled zone is that there is a rather firm top coating on the debris pile. Once that top coating is removed through the removal tool circulation patterns, the balance of the debris becomes somewhat fluidized. The present invention adds a lower end device that initially contacts the top of the debris pile and can somewhat embed into it while giving a weight signal at the surface while at the same time providing side openings that are large enough to allow the needed circulation for debris pickup. The device can be telescoping nested tubes that are extended with the pressure from circulation flow. There can be a bias toward the minimum telescoped dimension when there is no pressure available from circulation. As debris collection continues the surface personnel can control the process with the brake so that the downward movement of the tool can be regulated to the rate that the debris is removed. Another option is to put sensors that measure the amount of extension of the telescoping assembly and transmit that information to the surface. The surface personnel can then work the brake to control the amount of telescoping assembly extension to provide the optimum spacing of the collection tool to the top of the heap of debris. The lateral outlets can be in the lowest telescoping component and the lowest component can be tall enough above the top ends of the lateral slots so that some telescoping of the next higher tubular will not reduce the area of the lateral slots in the lowest telescoping component. These and other aspects of the present invention will be more readily apparent from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.

SUMMARY OF THE INVENTION

A spacing device is located on a lower end of a debris removal tool. Circulation through the tool extends telescoping members to the top of the debris zone against a bias that retracts the members when there is no flow through the tool. The lowest telescoping member has peripheral slots through which the circulation for the tool takes place. The landing of the tool on top of the debris can be detected by the weight indicator at the surface. The device prevents embedding the lower end of the tool into the debris. Instruments can also determine the scope of the telescoping extension and transmit that value to the surface so that the cleanup tool can be continuously spaced from the moving top of the debris pile by maintaining a target distance for extension of the telescoping assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a debris cleanup tool having the device of the present invention on the lower end;

FIG. 2 is a more detailed view of the debris cleanup device shown in FIG. 1;

FIG. 3 shows a telescoping assembly used with the cleanup tool in FIG. 1 where flow around the outside of the tool is in a direction toward the debris;

FIG. 4 shows a telescoping assembly used with a cleanup tool where the flow is through the tool and in a direction toward the debris.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a wellbore cleanup tool 10 that is supported from a string 12 in a wellbore 14 that has debris 16 that needs to be removed. This tool is made by Baker Hughes and is known as a Vectored Annulus Cleaning System (VACS) tool. Its operation is illustrated in several of the above cited patents and is reviewed in general terms using FIG. 2. Arrow 18 represents motive fluid coming down the string 12. Arrows 20 show a lateral exit that creates an eductor to draw fluid represented by arrow 22. After making a lateral exit, the fluid stream represented by arrow 22 splits with some going downhole shown by arrow 24 and the rest going uphole represented by arrow 26. The flow represented by arrow 24 goes down the outside of the tool and enters a lower end to bring in debris 16 into the tool body as represented by arrow 28. The debris laden fluid enters and passes through a riser pipe 30 that has an open top 32. Arrow 34 represents the heavier solids falling into an annular space 36. The fluid with smaller debris still entrained rises as indicated by arrow 38 and passes through the screen 40 leaving the smaller debris behind where such debris ultimately falls into the annular space 36 when fluid circulation stops. Arrow 22 is the clean fluid that is educted through the screen 40 to mix with the incoming fluid stream represented by arrow 18 and make the lateral exit described before. Again, this tool is well known and covered by several patents and provides the framework for the present invention. Other types of debris gathering tools can also be used with the present invention and the use of the VACS tool in this description is purely illustrative. Other tool types than debris collection tools can also be used where spacing of the tool from the debris is needed to allow the tool to operate.

FIG. 1 shows the telescoping device 42 secured at the lower end of the cleanup tool 10 while FIG. 3 shows that version of the tool 42 in greater detail. Referring to FIG. 3 there are three illustrated tubular telescoping sections 44, 46 and 48. Those skilled in the art recognize that additional or fewer sections can be used as well as a single section without any telescoping capability. The sections 44, 46 and 48 can coaxially or eccentrically telescope. The lowermost section 48 has a plurality of peripheral slots 50 that begin at the lower end 52 although the slots can alternatively begin above the end 52. FIGS. 3 and 4 are not to scale and it is preferred that the top 54 of the slots 50 leave a blank area in section 48 above the slot top so that fully telescoping section 46 into section 48 will still leave the slots 50 fully open. The arrows 24 in FIG. 3 represent the flow toward the debris 16 and outside the tool 10 as previously discussed. The surrounding pressure represented by arrows 24 acts on ledges 56, 58 and 60 to promote extension of the assembly 42 when the pumps are on at the surface. The weight of the sections 44, 46 and 48 also works to extend them even when there is no pressure from circulation. As an alternative there can be a mechanical drive that extends or retracts the assembly 42. A spring bias shown schematically as 62 can also hold the sections 44, 46 and 48 in the shown extended position. The top 64 of the debris layer 16 is shown in FIG. 3 with the lower end 52 adjacent to the top 64. There is normally circulation when the tool 10 is being lowered so that the assembly 42 is extended. As the top 64 is encountered, the end 52 can either stay on the top if the top 64 is initially firm enough or the end 52 can somewhat penetrate the top 64. The contact at 64 with or without penetration is seen in the weight indicator at the surface. As that happens, the surface personnel apply the brake (not shown) to slow or stop the advance of the tool 10. From that point the rig crew can simply watch the weight indicator and lower the tool 10 at a comparable rate to the removal of the debris by targeting a weight range on the weight indicator. If they lower a little too fast then the assembly 42 telescopes shorter while leaving open the slots 50. This can go on until assembly 42 is fully compressed before the indicated weight will go down as a signal that the tool 10 is advanced too far into the debris 16. Another operating mode can be to compress the assembly 42 using the weight indicator reading and then just holding the tool 10 in position as the device 42 extends to its full extension at which point the weight indication will decrease and the tool 10 can be lowered a distance that will fully or partly compress the device 42. In that manner the lower end 52 will ride with the decreasing level 64 of the debris 16.

A more elaborate control scheme is shown schematically as a sensor S and a way of transmitting the signal to the surface, shown schematically as arrow 66. The sensing can be of the amount of extension of the assembly 42. In that case the surface personnel can target maintaining the extension at some level below maximum and well above the minimum extension. In doing that the proper extension of the assembly 42 is maintained. The signal to the surface can be on wire or fiber optic or control line, to name a few possibilities. The sections 44, 46 and 48 can also be driven such as with a motor and a rack and pinion system although greater simplicity is always preferred for enhanced reliability. Preferably at the minimum dimension the slots 50 will not be obstructed by the sections 44 and 46.

FIG. 4 has the flow regime and the telescoping member stacking inverted so that internal pressure represented by arrows 68 acts on internal radial surfaces such as 70 to hold the position shown in FIG. 4 when there is flow. Again the weight of the components will urge them to extend but there can also be a bias such as 62 to urge the contraction of the telescoping elements.

Those skilled in the art will appreciate that the device 42 in the various alternatives described is used to properly distance the tool 10 that is preferably a debris removal tool from the top of the pile of debris to be collected so that the tool functions more optimally. The operation of the device 42 can be regulated from either watching the weight indicator at the surface or from getting a surface signal as to the degree of extension of the assembly as the debris removal progresses and as the tool 10 is allowed to advance by the surface crew. The device 42 can telescope by pressure from circulation or collapse by set down weight or a spring bias that operated when there is no flow to urge telescopic extension. The components can be mechanically extended or retracted with appropriate instrumentation to avoid overstressing a driver such as a motor connected to, for example, a pinion that engages a rack on the various components.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below. 

We claim:
 1. A spacer for a lower end of a subterranean removal tool for debris, comprising: a tubular housing defined by a wall having an open upper and lower end, the upper end supported by the tool and further comprising at least one opening in said wall so that when said lower end is in contact with the debris to be removed, fluid flow with respect to the tool with entrained debris can occur through said opening while spacing the tool from the debris.
 2. The spacer of claim 1, wherein: said housing has multiple components.
 3. The spacer of claim 2, wherein: said components coaxially or eccentrically telescope.
 4. The spacer of claim 3, wherein: said components move responsive to pressure that creates fluid flow.
 5. The spacer of claim 4, wherein: said components extend with respect to each other responsive to pressure that creates fluid flow.
 6. The spacer of claim 5, wherein: said components are biased toward a collapsed position.
 7. The spacer of claim 3, wherein: said opening remains open when said components fully collapse.
 8. The spacer of claim 7, wherein: said opening remains fully open when said components are fully extended or fully collapsed.
 9. The spacer of claim 8, wherein: said opening comprises at least one slot located on a lowermost component of said components.
 10. The spacer of claim 9, wherein: said at least one slot comprises a plurality of slots extending up from at or near lower end of said lowermost component.
 11. The spacer of claim 3, further comprising: a sensor to detect the amount of telescoping of said components; a transmitter to a surface location of the reading of said sensor of the degree of telescoping extension.
 12. The spacer of claim 11, wherein: said sensor allows a lowermost component of said housing to stay in contact with a top surface of the debris as debris is removed into the tool.
 13. A method of operating a debris removal tool at a subterranean location comprising: connecting a spacer near a lower end of the debris removal tool; configuring the spacer to have at least one wall opening; running in the tool to a location where the spacer engages a top surface of debris at the subterranean location; using said spacer to hold a lower end of the debris removal tool from the debris top surface while flow goes through said opening for retaining the debris in the tool.
 14. The method of claim 13, comprising: using multiple coaxially or eccentrically telescoping components for said spacer.
 15. The method of claim 14, comprising: placing said wall opening in a lowermost component of said components.
 16. The method of claim 14, comprising: using pressure from said flow to extend said telescoping components.
 17. The method of claim 14, comprising: keeping said opening at least part way open when said components telescope to their shortest dimension.
 18. The method of claim 14, comprising: positioning a lower end of a lowermost component on a debris top surface with said components telescoped in; allowing said components to telescope out to maintain contact of said lowermost component with the moving top of the debris as debris is collected in the tool while the tool is held stationary; lowering the tool after said components telescopingly extend to allow said lowermost component to remain in contact with the moving top of the debris.
 19. The method of claim 14, comprising: sensing the amount of extension of said telescoping components; transmitting to a surface location the sensed amount of extension of said telescoping components; using the transmitted information to maintain a lowermost component in contact with a moving top surface of the debris as debris is removed and the tool is moved.
 20. The method of claim 18, comprising: sensing the amount of extension of said telescoping components; transmitting to a surface location the sensed amount of extension of said telescoping components; using the transmitted information to maintain a lowermost component in contact with a moving top surface of the debris as debris is removed and the tool is moved. 